Process of manufacturing a trimmer capacitor

ABSTRACT

A single length of profiled stock is machined in a single operation with a single tool to form a rotor portion and a stator portion integral therewith. The rotor and stator portions are subsequently separated from each other by an axial cut and a transverse cut. The separated rotor and stator portions are assembled to form a trimmer capacitor.

I United States Patent [l 3,675,288 Trouser [4 1 July 11, 1972 I PROCESS OF MANUFACTURING A 3,129,364 4/1964 Oxley 317/253 TRIMMER CAPACITOR 3.262033 7/1966 Culbertson 317 253 lnvcnmr 754] Engelsbrand Primary Examiner-John F. Campbell y Assistant Examiner-Carl E. Hall [22] Filed: Sept. 23, 1970 Attorney-Spencer & Kaye 2| A l. N r: 74,769 I PP 57 ABSTRACT 52 11.5.0 ..29/25.4| 29/416 29/418 A single *"E 0f Profled Stock is machmed a Single I 7/253 tion with a single tool to form a rotor portion and a stator por 51 1m, un 13/00 tion integral therewith. The rotor and stator portions are sub- 2 /25.4l.4l6,4ll3; 317/251, sequently separated from each other by an axial cut and a 3 l 7/252, 253, 254 transverse cut. The separated rotor and stator portions are assembled to foml a trimmer capacitor. 56] References Cited UNITED STATES PATENTS 1 Claim, 3 Drawing Figures PKTENTEDJHL 11 m2 3. 675.288

NVIE TOR Alfred Tronser mw'yfi ATTORNEYS.

PROCESS OF MANUFACTURING A TRIMMER CAPACZITOR This invention relates to a process of manufacturing trimmer capacitors.

It is known to manufacture trimmer capacitor which comprises a rotor and a stator which are milled or turned from profiled stock. In that known process, different profiled stock must be used for the rotor and the stator so that these two parts must be made in two separate operations.

This gives rise to the necessity to maintain so close tolerances for the tool sets used to mill the rotor and stator plates that the spacing of the milled rotor and stator plates are substantially the same. In the finished capacitor, the rotor plates move into the spaces between the stator plates and the resulting air gaps should be of equal width throughout the set of plates whereas the use of a plurality of tool sets having larger tolerances results in differences in the size of these gaps. The occurrence of such differences limits the number of plates which may be used and imposes a lower limit on the width of the air gap. These two parameters are of great significance for the utility of the trimmer capacitors because the number of plates determines the capacitance range and the air gap determines the overall height.

In the process according to the invention, this difficulty is eliminated in that rotor and stator portions are machined in a single operation in a single piece of profiled stock by means of a single tool and are subsequently separated by an axial cut and a horizontal cut.

An embodiment of the invention is shown by way of example diagrammatically and partly in section in the drawing, in which FIG. 1 is a transverse sectional view showing a length of profiled stock in which a rotor and stator are jointly machined.

FIG. 2 is a longitudinal sectional view showing the machined length of profiled stock.

FIG. 3 is a side elevation showing a finished trimmer capacitor.

In the length of profiled material shown in FIG. 1, the rotor portion is designated 2 and the stator portion is designated 3. When the machining operation has been performed, the stator and rotor are separated by an axial cut taken on line 4 and a transverse cut taken on line 5 and are assembled in known manner to form the complete trimmer capacitor shown in FIG. 3.

The mode of manufacture is applicable to normal trimmer capacitors having a linear capacitance curve or a nonlinear capacitance curve The method of manufacture may also be used to make differential capacitors and butterfly capacitors. In these cases, it will be sufficient to change the profile of the raw material,

lclaim:

l. A process for manufacturing a trimmer capacitor having a rotor and a stator, each of which comprises a plurality of spaced plates held together by a common integral portion comprising the steps of:

a. machining a single length of profiled stock in a single operation with a single tool to fonn the plates of both a rotor portion and a stator portion of said length, said rotor and stator portions being integral with one another and with the rotor and stator plates extending away from one another;

b. cutting the machined stock in the direction of its length, from one end thereof, along a plane between the rotor and stator plates, to a point intermediate the ends of the stock, and also cutting the machined stock in a direction transverse to the length of the stock, from a side edge thereof, and along a plane passing through the intermediate point, so as to separate the rotor and stator portions; and

c. assembling the separated rotor and stator portions to form a trimmer capacitor, 

1. A process for manufacturing a trimmer capacitor having a rotor and a stator, each of which comprises a plurality of spaced plates held together by a common integral portion comprising the steps of: A. MACHINING A SINGLE LENGTH OF PROFILED STOCK IN A SINGLE OPERATION WITH A SINGLE TOOL TO FORM THE PLATES OF BOTH A ROTOR PORTION AND A STATOR PORTION OF SAID LENGTH, SAID ROTOR AND STATOR PORTIONS BEING INTEGRAL WITH ONE ANOTHER AND WITH THE ROTOR AND STATOR PLATES EXTENDING AWAY FROM ONE ANOTHER; B. CUTTING THE MACHINED STOCK IN THE DIRECTION OF ITS LENGTH, FROM ONE END THEREOF, ALONG A PLANE BETWEEN THE ROTOR AND STATOR PLATES, TO A POINT INTERMEDIATE THE ENDS OF THE STOCK, AND ALSO CUTTING THE MACHINED STOCK IN A DIRECTION TRANSVERSE TO THE LENGTH OF THE STOCK, FROM A SIDE EDGE THEREOF, AND ALONG A PLANE PASSING THROUGH THE INTERMEDIATE POINT, SO AS TO SEPARATE THE ROTOR AND STATOR PORTIONS; AND C. ASSEMBLING THE SEPARATED ROTOR AND STATOR PORTIONS TO FORM A TRIMMER CAPACITOR. 